| 摘要 |
PURPOSE:To simplify the detection of moisture and to achieve cost reduction, by enclosing a heater and a temp. sensor in a cylindrical container made of a metal and plastic and discharging heat from the heater pulsatively and measuring the change in the quantity of heat in the container by the sensor. CONSTITUTION:A cylindrical container closed at one end thereof is divided into a metal part 3 and a plastic part 4, and a heater 1 and a temp. sensor 2 are fixed to the container so as to be brought into contact with the metal part 3 and a lead wire is drawn out from the other end of the container. The container is inserted in a water absorbing and holding material and the heater 1 is operated only for several min to measure the quantity of heat received by the sensor 2 as output voltage. Said heat is also simultaneously escaped to the water absorbing and holding material in contact with the metal part 3 and the heat remaining in the metal part 3 imparts change to the sensor 2. Therefore, by measuring the change in the output voltage of the sensor 2, water content can be detected and, when the sensitivity or the position of the sensor 2 is changed, this detector can correspond to the change in water content. By this method, a structure can be made simple and inexpensive. |
